This invention is directed to a new and improved homogeneous material circuit board or sheet having a first circuit pattern element or elements supported on one side thereof and making surface contact therethrough to contacts or other isolated circuit patterns in surface contact with the other side thereof where aligned with and opposed to portions of the first circuit pattern element or elements.
The board or sheet of this invention comprises a binder e.g., plastic, in which electrically conductive particles are homogeneously dispersed.
In the past, in order to make contact from elements on one side of a circuit board to elements on the other side of a circuit board, eyelets or other material which extended from one surface of the board to the opposite surface were provided.
The present invention does away with the requirement of such direct connections in that the board of this invention has a low through resistance between aligned and opposed contacts e.g., screen and inked or plated on contacts adhering to opposite surfaces thereof.
At the same time the sheet will permit isolated contacts positioned on the same side of the board and in contact therewith to remain isolated from each other when positioned an isolation distance apart from each other.
In this invention surface contact or touching need only be made to the sheet and compression of the volume of the board or sheet between opposing contacts to force electrically conductive particles together in the sheet is not necessary to achieve conduction or low through resistance, e.g., electrical contacts need only be screened on both sides of the sheet to effect contacting from one side of the sheet to the other side of the sheet where the circuit patterns are aligned and opposed.
The circuit board or sheet of the present invention can be termed an isolated path board in that it exhibits a low through resistance in a volume between aligned opposing surface contacts on opposite sides of the sheet and exhibits a higher isolation resistance in all volumes thereof at a distance greater than about the thickness of the sheet. Thus electrical contacts e.g., circuit pattern portions positioned apart from each other on the same side of the sheet at a distance greater than about the thickness of the sheet (an isolation distance apart) are electrically isolated from each other even though another contact on the opposite side of the sheet and aligned with respect to one of said circuit pattern portions will be electrically coupled through a low resistance portion of the board to said aligned and opposed circuit pattern portions.
In view of the foregoing mentioned properties of the sheet of this invention it is now possible to make electrical contact between a plurality of aligned contacts of first and second circuit patterns adhered to the sheet and in surface contact therewith or a plurality of elements of one circuit pattern and the contacts of an electrical device positioned merely in surface electrical contact with the opposite side of the sheet and in alignment with elements of said one circuit pattern.